/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.metadata.logfile;

import org.apache.iotdb.commons.file.SystemFileFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Files;

/**
 * This class provides the common ability to write a log storing T.
 *
 * @param <T>
 */
public class SchemaLogWriter<T> implements AutoCloseable {

    private static final Logger LOGGER = LoggerFactory.getLogger(SchemaLogWriter.class);

    private final File logFile;

    private final FileOutputStream fileOutputStream;

    private final ISerializer<T> serializer;

    private final boolean forceEachWrite;

    private boolean hasSynced = true;

    public SchemaLogWriter(
            String schemaDir, String logFileName, ISerializer<T> serializer, boolean forceEachWrite)
            throws IOException {
        File dir = SystemFileFactory.INSTANCE.getFile(schemaDir);
        if (!dir.exists()) {
            if (dir.mkdirs()) {
                LOGGER.info("create schema folder {}.", dir);
            } else {
                LOGGER.warn("create schema folder {} failed.", dir);
            }
        }

        logFile = SystemFileFactory.INSTANCE.getFile(schemaDir + File.separator + logFileName);
        fileOutputStream = new FileOutputStream(logFile, true);
        this.serializer = serializer;

        this.forceEachWrite = forceEachWrite;
    }

    public SchemaLogWriter(String logFilePath, ISerializer<T> serializer, boolean forceEachWrite)
            throws IOException {
        logFile = SystemFileFactory.INSTANCE.getFile(logFilePath);
        fileOutputStream = new FileOutputStream(logFile, true);
        this.serializer = serializer;

        this.forceEachWrite = forceEachWrite;
    }

    public synchronized void write(T schemaPlan) throws IOException {
        hasSynced = false;
        // serialize plan to binary data
        serializer.serialize(schemaPlan, fileOutputStream);

        if (forceEachWrite) {
            syncBufferToDisk();
        }
    }

    public synchronized void force() throws IOException {
        if (hasSynced) {
            return;
        }
        hasSynced = true;
        fileOutputStream.getFD().sync();
    }

    private void syncBufferToDisk() throws IOException {
        fileOutputStream.getFD().sync();
        hasSynced = true;
    }

    public synchronized void clear() throws IOException {
        fileOutputStream.close();

        if (logFile != null && logFile.exists()) {
            Files.delete(logFile.toPath());
        }
    }

    @Override
    public synchronized void close() throws IOException {
        fileOutputStream.close();
    }
}
